To many people, quantum computers are considered the holy grail of information technology. They would be able to solve problems and break secret codes using quantum mechanics— taking them a fraction of a second compared to the decades it would take modern technology. We don’t have these computers (yet), but we already have its smallest component, the qubit.

Imagine driving across the United States without a map or GPS. How would you do it? How would you know where you are and how far you had to go? As impossible as this feat seems, millions of birds perform it every year. Traversing thousands of miles on annual migrations, Arctic terns, bar-tailed godwits, and ruby-throated hummingbirds seem to know exactly where they are going, yet for years scientists had no idea how they did it. One physicist, Klaus Schulten, thought one explanation might be that the birds could sense the Earth’s magnetic fields, perhaps using magnetite molecules in their eyes. But no one knew how that was possible. Recent research may provide a clue. Scientists now have evidence suggesting that at least some birds use quantum mechanics, the weird rules that govern the behavior of the microscopic world. A 2004 experiment involving robins showed that an extremely weak magnetic field could throw off the birds’ navigation abilities, an effect that made no sense if magnetite molecules provided the guidance, but fit perfectly with a model involving quantum entanglement, a subatomic process that allows widely separated objects to influence each other. In this model, when a photon of light enters …

Brian Greene continues the WSF Live Forum all month long. Each day, he’ll answer one of your questions for this ongoing series that delves into the fundamental nature of space, time, and reality as we may or may not know it. Why are so many physicists chasing string theory when, after 30+ years, there is still no means of testing it? —C Gulow (via BoingBoing) The primary goal of string theory is to join the laws of quantum mechanics (the laws of the “small”) with the laws of general relativity (the laws of the “large”), into a single mathematically consistent framework. This is vital because in the standard formulation (without string theory, say), the union of quantum mechanics and general relativity leads to mathematical inconsistencies, sort of like what happens on a calculator if you divide 1 by 0. And since the universe is surely consistent, we need a mathematical description that’s consistent too. Without such a consistent formulation, for example, we don’t stand a chance of fully understanding the origin of the universe or what happens in the deep interior of black holes. Melding quantum mechanics and general relativity is a tough nut to crack; to date, very few …

Brian Greene continues the WSF Live Forum all month long. Each day, he’ll answer one of your questions for this ongoing 2011 series that delves into the fundamental nature of space, time, and reality as we may or may not know it. Brian, what was the driving force that made you who you are as a physicist? My intended major is physics, and it can become weird at times as much as I love it. What do you recommend me to do while I attend a community college? I really want to become a famous physicist like you with my passion for physics. —Kenneth Rosario-Gonzalez, Tampa, Florida There were two forces that drove me to physics. The first was a love of numbers. When early on my dad taught me the basics of arithmetic, I was amazed that with just paper and pencil you could endlessly do new things. I remember when I was about 5, I’d tape together many large sheets of construction paper on which I’d spend days multiplying two 30 digit numbers. I found it captivating to do a calculation that, more than likely, no one had ever done before. And with good reason—the calculation wasn’t particularly …